(function (exports, ByteArray, global) {
    var Protocol = exports;

    var PKG_HEAD_BYTES = 4;
    var MSG_FLAG_BYTES = 1;
    var MSG_ROUTE_CODE_BYTES = 2;
    var MSG_ID_MAX_BYTES = 5;
    var MSG_ROUTE_LEN_BYTES = 1;

    var MSG_ROUTE_CODE_MAX = 0xffff;

    var MSG_COMPRESS_ROUTE_MASK = 0x1;
    var MSG_TYPE_MASK = 0x7;

    var Package = Protocol.Package = {};
    var Message = Protocol.Message = {};

    Package.TYPE_HANDSHAKE = 1;
    Package.TYPE_HANDSHAKE_ACK = 2;
    Package.TYPE_HEARTBEAT = 3;
    Package.TYPE_DATA = 4;
    Package.TYPE_KICK = 5;

    Message.TYPE_REQUEST = 0;
    Message.TYPE_NOTIFY = 1;
    Message.TYPE_RESPONSE = 2;
    Message.TYPE_PUSH = 3;

    /**
     * pomele client encode
     * id message id;
     * route message route
     * msg message body
     * socketio current support string
     */
    Protocol.strencode = function(str) {
        var byteArray = new ByteArray(str.length * 3);
        var offset = 0;
        for(var i = 0; i < str.length; i++){
            var charCode = str.charCodeAt(i);
            var codes = null;
            if(charCode <= 0x7f){
                codes = [charCode];
            }else if(charCode <= 0x7ff){
                codes = [0xc0|(charCode>>6), 0x80|(charCode & 0x3f)];
            }else{
                codes = [0xe0|(charCode>>12), 0x80|((charCode & 0xfc0)>>6), 0x80|(charCode & 0x3f)];
            }
            for(var j = 0; j < codes.length; j++){
                byteArray[offset] = codes[j];
                ++offset;
            }
        }
        var _buffer = new ByteArray(offset);
        copyArray(_buffer, 0, byteArray, 0, offset);
        return _buffer;
    };

    /**
     * client decode
     * msg String data
     * return Message Object
     */
    Protocol.strdecode = function(buffer) {
        var bytes = new ByteArray(buffer);
        var array = [];
        var offset = 0;
        var charCode = 0;
        var end = bytes.length;
        while(offset < end){
            if(bytes[offset] < 128){
                charCode = bytes[offset];
                offset += 1;
            }else if(bytes[offset] < 224){
                charCode = ((bytes[offset] & 0x3f)<<6) + (bytes[offset+1] & 0x3f);
                offset += 2;
            }else{
                charCode = ((bytes[offset] & 0x0f)<<12) + ((bytes[offset+1] & 0x3f)<<6) + (bytes[offset+2] & 0x3f);
                offset += 3;
            }
            array.push(charCode);
        }
        return String.fromCharCode.apply(null, array);
    };

    /**
     * Package protocol encode.
     *
     * Pomelo package format:
     * +------+-------------+------------------+
     * | type | body length |       body       |
     * +------+-------------+------------------+
     *
     * Head: 4bytes
     *   0: package type,
     *      1 - handshake,
     *      2 - handshake ack,
     *      3 - heartbeat,
     *      4 - data
     *      5 - kick
     *   1 - 3: big-endian body length
     * Body: body length bytes
     *
     * @param  {Number}    type   package type
     * @param  {ByteArray} body   body content in bytes
     * @return {ByteArray}        new byte array that contains encode result
     */
    Package.encode = function(type, body){
        var length = body ? body.length : 0;
        var buffer = new ByteArray(PKG_HEAD_BYTES + length);
        var index = 0;
        buffer[index++] = type & 0xff;
        buffer[index++] = (length >> 16) & 0xff;
        buffer[index++] = (length >> 8) & 0xff;
        buffer[index++] = length & 0xff;
        if(body) {
            copyArray(buffer, index, body, 0, length);
        }
        return buffer;
    };

    /**
     * Package protocol decode.
     * See encode for package format.
     *
     * @param  {ByteArray} buffer byte array containing package content
     * @return {Object}           {type: package type, buffer: body byte array}
     */
    Package.decode = function(buffer){
        var offset = 0;
        var bytes = new ByteArray(buffer);
        var length = 0;
        var rs = [];
        while(offset < bytes.length) {
            var type = bytes[offset++];
            length = ((bytes[offset++]) << 16 | (bytes[offset++]) << 8 | bytes[offset++]) >>> 0;
            var body = length ? new ByteArray(length) : null;
            copyArray(body, 0, bytes, offset, length);
            offset += length;
            rs.push({'type': type, 'body': body});
        }
        return rs.length === 1 ? rs[0]: rs;
    };

    /**
     * Message protocol encode.
     *
     * @param  {Number} id            message id
     * @param  {Number} type          message type
     * @param  {Number} compressRoute whether compress route
     * @param  {Number|String} route  route code or route string
     * @param  {Buffer} msg           message body bytes
     * @return {Buffer}               encode result
     */
    Message.encode = function(id, type, compressRoute, route, msg){
        // caculate message max length
        var idBytes = msgHasId(type) ? caculateMsgIdBytes(id) : 0;
        var msgLen = MSG_FLAG_BYTES + idBytes;

        if(msgHasRoute(type)) {
            if(compressRoute) {
                if(typeof route !== 'number'){
                    throw new Error('error flag for number route!');
                }
                msgLen += MSG_ROUTE_CODE_BYTES;
            } else {
                msgLen += MSG_ROUTE_LEN_BYTES;
                if(route) {
                    route = Protocol.strencode(route);
                    if(route.length>255) {
                        throw new Error('route maxlength is overflow');
                    }
                    msgLen += route.length;
                }
            }
        }

        if(msg) {
            msgLen += msg.length;
        }

        var buffer = new ByteArray(msgLen);
        var offset = 0;

        // add flag
        offset = encodeMsgFlag(type, compressRoute, buffer, offset);

        // add message id
        if(msgHasId(type)) {
            offset = encodeMsgId(id, buffer, offset);
        }

        // add route
        if(msgHasRoute(type)) {
            offset = encodeMsgRoute(compressRoute, route, buffer, offset);
        }

        // add body
        if(msg) {
            offset = encodeMsgBody(msg, buffer, offset);
        }

        return buffer;
    };

    /**
     * Message protocol decode.
     *
     * @param  {Buffer|Uint8Array} buffer message bytes
     * @return {Object}            message object
     */
    Message.decode = function(buffer) {
        var bytes =  new ByteArray(buffer);
        var bytesLen = bytes.length || bytes.byteLength;
        var offset = 0;
        var id = 0;
        var route = null;

        // parse flag
        var flag = bytes[offset++];
        var compressRoute = flag & MSG_COMPRESS_ROUTE_MASK;
        var type = (flag >> 1) & MSG_TYPE_MASK;

        // parse id
        if(msgHasId(type)) {
            var m = parseInt(bytes[offset]);
            var i = 0;
            do{
                var m = parseInt(bytes[offset]);
                id = id + ((m & 0x7f) * Math.pow(2,(7*i)));
                offset++;
                i++;
            }while(m >= 128);
        }

        // parse route
        if(msgHasRoute(type)) {
            if(compressRoute) {
                route = (bytes[offset++]) << 8 | bytes[offset++];
            } else {
                var routeLen = bytes[offset++];
                if(routeLen) {
                    route = new ByteArray(routeLen);
                    copyArray(route, 0, bytes, offset, routeLen);
                    route = Protocol.strdecode(route);
                } else {
                    route = '';
                }
                offset += routeLen;
            }
        }

        // parse body
        var bodyLen = bytesLen - offset;
        var body = new ByteArray(bodyLen);

        copyArray(body, 0, bytes, offset, bodyLen);

        return {'id': id, 'type': type, 'compressRoute': compressRoute,
            'route': route, 'body': body};
    };

    var copyArray = function(dest, doffset, src, soffset, length) {
        if('function' === typeof src.copy) {
            // Buffer
            src.copy(dest, doffset, soffset, soffset + length);
        } else {
            // Uint8Array
            for(var index=0; index<length; index++){
                dest[doffset++] = src[soffset++];
            }
        }
    };

    var msgHasId = function(type) {
        return type === Message.TYPE_REQUEST || type === Message.TYPE_RESPONSE;
    };

    var msgHasRoute = function(type) {
        return type === Message.TYPE_REQUEST || type === Message.TYPE_NOTIFY ||
            type === Message.TYPE_PUSH;
    };

    var caculateMsgIdBytes = function(id) {
        var len = 0;
        do {
            len += 1;
            id >>= 7;
        } while(id > 0);
        return len;
    };

    var encodeMsgFlag = function(type, compressRoute, buffer, offset) {
        if(type !== Message.TYPE_REQUEST && type !== Message.TYPE_NOTIFY &&
            type !== Message.TYPE_RESPONSE && type !== Message.TYPE_PUSH) {
            throw new Error('unkonw message type: ' + type);
        }

        buffer[offset] = (type << 1) | (compressRoute ? 1 : 0);

        return offset + MSG_FLAG_BYTES;
    };

    var encodeMsgId = function(id, buffer, offset) {
        do{
            var tmp = id % 128;
            var next = Math.floor(id/128);

            if(next !== 0){
                tmp = tmp + 128;
            }
            buffer[offset++] = tmp;

            id = next;
        } while(id !== 0);

        return offset;
    };

    var encodeMsgRoute = function(compressRoute, route, buffer, offset) {
        if (compressRoute) {
            if(route > MSG_ROUTE_CODE_MAX){
                throw new Error('route number is overflow');
            }

            buffer[offset++] = (route >> 8) & 0xff;
            buffer[offset++] = route & 0xff;
        } else {
            if(route) {
                buffer[offset++] = route.length & 0xff;
                copyArray(buffer, offset, route, 0, route.length);
                offset += route.length;
            } else {
                buffer[offset++] = 0;
            }
        }

        return offset;
    };

    var encodeMsgBody = function(msg, buffer, offset) {
        copyArray(buffer, offset, msg, 0, msg.length);
        return offset + msg.length;
    };

    if(typeof(window) != "undefined") {
        window.Protocol = Protocol;
    }
})(typeof(window)=="undefined" ? module.exports : (this.Protocol = {}),typeof(window)=="undefined"  ? Buffer : Uint8Array, this);